In the field of electrophotography, with the progress of electrophotographic systems, it has been demanded to develop toners for development of electrostatic images adaptable for high image quality and high copying or printing speed.
In patent literature 1, a method for producing a toner for electrophotography including a step of melt-kneading toner raw material containing a binder resin having a softening point of 90 to 120° C., a colorant, and a wax having a melting point of 60 to 100° C., wherein the binder resin contains a linear polyester obtained by condensation polymerization of a carboxylic acid component containing 50 mol % or more of fumaric acid and/or maleic acid and an alcohol component; the content of the wax is 4 parts by weight or less on the basis of 100 parts by weight of the binder resin; the melt-kneading process is carried out by using an open-roll type kneading machine having two rolls having a different temperature from each other; and in one roll having a higher temperature in an upstream side of kneading in the open-roll type kneading machine, the set temperature in the upstream side of kneading is not higher than the softening point of the binder resin, and the set temperature in the downstream side of kneading is not lower than the melting point of the wax, with a ratio of the set temperatures in the upstream side and the downstream side {(set temperature (° C.) in the upstream side)/(set temperature (° C.) in the downstream side)} being 1.0 to 1.5 is written. It is written that according to the production method, a good color image having good low-temperature fusing property even under a low pressurizing force on fusing and having excellent color reproducibility is obtained.
In patent literature 2, a process for making a toner resin including: reacting an organic diol with a cyclic alkylene carbonate in the presence of a first catalyst to form a polyalkoxy diol; reacting the polyalkoxy diol with one or more diacid reagents in the presence of a second catalyst in an esterification reaction; monitoring an acid value of a resulting mixture from the esterification reaction; and subsequently polycondensing the resulting mixture with an unsaturated diacid to form an unsaturated polyester resin is written.
In patent literature 3, a developing agent including toner particles including a binder resin including a first polyester resin synthesized from a first aromatic monomer and a first aliphatic monomer blended with a molar ratio in an alcohol component being satisfied with the relationship of {(aromatic monomer)>(aliphatic monomer)≥0} and with a molar ratio in an acid component being satisfied with the relationship of {(aliphatic monomer)>(aromatic monomer)}, a release agent, and a colorant is written. It is written that according to the developing agent, it is possible to improve fusing offset properties, light gloss, and storage properties at a high temperature.
In patent literature 4, an electrophotographic toner containing a crystalline resin, an amorphous resin, and a release agent, wherein the crystalline resin contains a crystalline composite resin C including a polycondensation-based resin component which is obtained by performing polycondensation of an alcohol component containing an aliphatic diol having a carbon number of 9 or more and 14 or less and a carboxylic acid component containing an aliphatic dicarboxylic acid compound having a carbon number of 9 or more and 14 or less, and a styrene-based resin component; the amorphous resin contains an amorphous composite resin A including a polycondensation-based resin component which is obtained by performing polycondensation of an alcohol component and a carboxylic acid component containing an aromatic dicarboxylic compound, and a styrene-based resin component; an average circularity of the toner is 0.940 or more; and the content of particles having a particle diameter of 3 μm or less in the toner is 5.0 number % or less is written. It is written that according to the toner is excellent in low-temperature fusing property and durability and is suppressed in wrapping of paper at the time of fusing.